In the past, ice cream cartons which are end-filling and top-opening, have had problems with leakage at the corners. During the filling operation, the ice cream is in a semi-viscous form and has not been solidly frozen as you would find in the stores. After leaving the filling machine, the ice cream carton is placed in a chiller which freezes the contents solid. During the solid freezing operation, the ice cream tends to leak from the carton ends at the corners and various areas where the flaps overlap. Thus, testing for leakage in a carton would be done by taking filled cartons and leaving them on a shelf at room temperature until ice cream begins to ooze from the bottom of the carton. Because of the susceptibility of leakage, it is important that the cartons reach the chiller as soon as possible in order to prevent leakage from starting at the ends. Different dairies have different packaging conditions and temperatures vary widely in different parts of the country. Thus the longer that leakage can be prevented, the less likelihood of rejection of certain cartons because of excess build-up of ice cream on the outside thereof. The purchaser does not want to see the ice cream on the outside of the carton and rejects those that are found packaged in this fashion.
It should also be noted, that different types of ice cream have different consistencies. Sherbet, for example, tends to melt much faster than heavier types of ice cream. Thus chilling of sherbet in the package becomes more critical than a heavy ice cream. The longer a leak can be prevented, the fewer rejects there are. Packing a large number of cartons adjacent each other in the chiller also creates a problem in that those cartons that are centrally located in a chiller, do not freeze as quickly as outer perimeter cartons. Contrary to popular belief, the ice cream carton itself is not sealed all around by some type of bonding agent such as glue or the like. The flaps, upon in-folding, are secured in an overlying manner by means of glue which is applied only to certain flaps and in a line. The glue is provided to prevent the flaps from flying open after closing. The glue does not overlie a seam in the carton as might be expected.
It should be stated, that the carton blank is formed into a sleeve which does have a glue line running the length of one panel thereof which bonds that panel to the flap having the tear-strip thereon. Thus leakage is not around the central portion of the carton but at the ends. Bosses have been used in the past to provide for proper closing of cartons so that when glue is applied, an adjacent flap surface will not be lower than the glue application surface of the initial flap portion; i.e. the adjacent flap area to which glue will be applied to and extended over onto the next flap. This can be readily seen in the use of bosses such as embosses in Buttery U.S. Pat. Nos. 3,524,581 and 3,735,916, De Paul 4,756,470.
Many patents have been granted to provide features which will delay leakage such as Froom U.S. Pat. Nos. 4,555,027, 4,712,689, 4,712,730, DePaul U.S. Pat. Nos. 4,756,470, 4,872,609, Capuano 4,819,864 and Hutchinson, et al. 4,757,902.